Across
- 4. water that is found beneath earth's surface
- 6. introduction of diseases and chemicals into water
- 10. area on earth that water percolates down into an aquifer
- 11. pollution discharged from a single source
- 13. inorganic plant nutrients,phosphorus and nitrogen enter water from sewage
- 14. land that is drained by a river
- 15. formed behind the dam
- 16. using water in machines and discharging water into river
- 17. built across rivers to control the river's flow
- 19. pesticides passed on to more organisms in the food chain
- 20. water that contains waste
Down
- 1. fresh water on earth's land
- 2. safe water to drink
- 3. removing salt from salt water
- 5. comes from many different sources that is difficult to identify
- 7. organisms that cause illness or disease
- 8. percentage of the total volume of a rock
- 9. rock or soil to allow water to flow through
- 12. flowing network of water
- 18. an underground formation that contains water